字符串转时间
iOS 中 NSDate 是时间管理类，这里获取到的时间是 UTC 时间，可以根据需要转换成任意地区的时间。
NSFormatter 类是时间格式化类，可以根据指定的格式、地区将指定的时间转换为 NSDate 对象
<code class="hljs vbscript has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;">NSString* <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">string</span> = @<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"20110826134106"</span>; NSDateFormatter *inputFormatter = [[[NSDateFormatter alloc] init] autorelease]; [inputFormatter <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">setLocale</span>:[[[NSLocale alloc] initWithLocaleIdentifier:@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"en_US"</span>] autorelease]]; [inputFormatter setDateFormat:@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"yyyyMMddHHmmss"</span>]; NSDate* inputDate = [inputFormatter dateFromString:<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">string</span>];</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li></ul>
时间格式转换
<code class="hljs bash has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;">NSString *dateStr = @<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"2015-11-25 00:00"</span>;NSDateFormatter *formatter = [[NSDateFormatter alloc] init];// [formatter <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">set</span>Locale:[[NSLocale alloc] initWithLocaleIdentifier:@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"en_US"</span>]];[formatter <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">set</span>DateFormat:@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"yyyy-MM-dd HH:mm"</span>];NSDate *date = [formatter dateFromString:dateStr];formatter = [[NSDateFormatter alloc] init];[formatter <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">set</span>DateFormat:@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"yyyy年MM月dd日"</span>];NSString *result = [formatter stringFromDate:date];</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li></ul>
获取本地时间
<code class="hljs lua has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;">NSDate *date = [NSDate date];NSDateFormatter *formatter = <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">[[NSDateFormatter alloc] init];[formatter setTimeZone:[NSTimeZone localTimeZone]]</span>;// [formatter setLocale:[NSLocale currentLocale]];NSString *result = [formatter stringFromDate:date];</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li></ul>
获取年月日
<code class="hljs objectivec has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"><span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSDate</span>*date = [<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSDate</span> date];<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSCalendar</span>*calendar = [<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSCalendar</span> currentCalendar];NSDateComponents*comps;<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 年月日获得</span>comps =[calendar components:(NSYearCalendarUnit | NSMonthCalendarUnit |NSDayCalendarUnit) fromDate:date];NSIntegeryear = [comps year];NSIntegermonth = [comps month];NSIntegerday = [comps day];</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li></ul>
时间格式
yy: 年的后2位
yyyy: 完整年
MM: 月，显示为1-12
MMM: 月，显示为英文月份简写,如 Jan
MMMM: 月，显示为英文月份全称，如 Janualy
dd: 日，2位数表示，如02
d: 日，1-2位显示，如 2
EEE: 简写星期几，如Sun
EEEE: 全写星期几，如Sunday
aa: 上下午，AM/PM
H: 时，24小时制，0-23
K：时，12小时制，0-11
m: 分，1-2位
mm: 分，2位
s: 秒，1-2位
ss: 秒，2位
S: 毫秒
地区（local identifier）
地区码 | 地区 | eu en_US美国zh_Hant_HK中国香港zh_Hans_CN中国大陆zh_Hant_TW中国台湾hr_BA
en_CM
rw_RW
en_SZ
tk_Latn
he_IL
ar
uz_Arab
en_PN
as
en_NF
rwk_TZ
gsw_LI
th_TH
ta_IN
es_EA
fr_GF
ar_001
en_RW
tr_TR
de_CH
ee_TG
en_NG
fr_TG
az
fr_SC
es_HN
en_AG
ru_KZ
gsw
dyo
so_ET
zh_Hant_MO
de_BE
km_KH
my_MM
mgh_MZ
ee_GH
es_EC
kw_GB
rm_CH
en_ME
nyn
mk_MK
bs_Cyrl_BA
ar_MR
en_BM
ms_Arab
en_AI
gl_ES
en_PR
ha_Latn_GH
ff_CM
ne_IN
or_IN
khq_ML
en_MG
pt_TL
en_LC
ta_SG
jmc_TZ
om_ET
lv_LV
es_US
en_PT
vai_Latn_LR
en_NL
iu_Cans_CA
cgg_UG
ta
en_MH
to_TO
zu_ZA
shi_Latn_MA
brx_IN
ar_KM
en_AL
te
chr_US
yo_BJ
fr_VU
pa
tg
ks_Arab
kea
ksh_DE
sw_CD
th
te_IN
fr_RE
ur_IN
yo_NG
ti
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tk
kl_GL
ksf_CM
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lag_TZ
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to
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ckb
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bez
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ckb_IQ
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ewo
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en_US_POSIX
yav_CM
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et_EE
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sg
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sn
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gv
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